The invention relates to an ink-supply device of a printing-machine inking unit, having a pressure discharge device including a cartridge holder for accepting a cartridge, the cartridge holder having a lid for closing the cartridge holder, the pressure discharge device being formed with an internal space subjectible to an application of compressed air to be applied to an internal space of the pressure discharge device via a flow path provided with a valve.
Devices of this general type having a cartridge as an ink reservoir are particularly advantageous if only very small quantities of a respective printing ink are used for specific print jobs. Pressure discharge units wherein the cartridge is pressed out by compressed air are very user-friendly.
The device described in the published European Patent Document EP 0 716 923 A1 includes a pressure discharge unit having a cylinder housing and a cover cap. A cartridge is insertable into the cylinder housing. The cylinder housing can be closed by screwing the cover cap there. Besides this specific screw connection, no other specific rotary joints, such as, a so-called wrench or twist (Renk) joint, for example, are described. Closing the cylinder housing by a general type of rotary joint, is likewise not mentioned. An interior space of the cover cap can have compressed air applied thereto via a manually actuatable valve which, for this purpose, is provided with a switch knob. The valve is not a multiway valve and has only a single flow path. No adjusting device for actuating the valve when the cylinder housing is closed by the lid is provided. Although the device is more user-friendly when compared with pressure discharge units constructed as handlever presses, because it requires no expenditure of force by the user in order to press out the cartridge, the operational reliability thereof is inadequate. On the one hand, inadvertent actuation of the switch knob and unintentionally leaving the compressed-air feed open are also possible when the cylinder housing has not been closed and when no cartridge has been inserted into the cylinder housing. The situation is therefore not ruled out wherein compressed air can continue to flow out of a pressure discharge unit even though the latter should actually be inactive, which may consequently cause pressure losses in the overall compressed-air system. On the other hand, one may forget to open the valve of an actually active pressure discharge unit when a cartridge is inserted into the cylinder housing. Operating faults of this type are often not noticed immediately, so that after the printing operation has been started, rejects are printed which have a printed image wherein the printing ink from the cartridge that is actually active but does not have compressed air applied thereto, and is therefore not pressed out, is lacking.
Furthermore, a device is described in the published German Patent Document DE 196 32 717 A1, wherein a cartridge can be inserted into a tubular housing. A fitted cap with a compressed-air connection can be set onto the tubular housing and locked on the housing by a bayonet lock-type mechanism.
It is accordingly an object of the invention to provide an ink-supply device of a printing-machine inking unit that can be operated more reliably than heretofore known devices of this general type.
With the foregoing and other objects in view, there is provided, in accordance with one aspect of the invention, an ink-supply device of a printing-machine inking unit, having a pressure discharge device, and a lid provided in the pressure discharge device for closing one of a cartridge holder for accepting a cartridge, and a cartridge received directly in the pressure discharge device, respectively, an internal space being formed in one of the pressure discharge device and in a region located between the cartridge and the lid, respectively, the internal space being subjectible to an application of compressed air via a flow path provided with a valve, comprising a setting device for actuating the valve when one of the cartridge holder and the cartridge, respectively, is closed by the lid.
In accordance with another aspect of the invention, there is provided an ink-supply device of a printing-machine inking unit, having a pressure discharge device including a cartridge holder for accepting a cartridge, the cartridge holder having a lid for closing the cartridge holder, the pressure discharge device being formed with an internal space subjectible to an application of compressed air to be applied to the internal space of the pressure discharge device via a flow path provided with a valve, comprising a setting device for actuating the valve when the cartridge holder is closed by the lid.
In accordance with a further aspect of the invention, there is provided an ink-supply device of a printing-machine inking unit, having a pressure discharge device for accepting a cartridge, the pressure discharge device having a lid for closing the cartridge directly, compressed air being applicable via a flow path provided with a valve to an internal space defined by the cartridge and the lid, comprising a setting device for actuating the valve when the cartridge is closed by the lid.
In accordance with an additional feature of the invention, the one of the cartridge holder and the cartridge, respectively, is constructed so to be closed by the lid via a releasable rotary joint, the valve being actuatable via the setting device when the rotary joint is rotated.
In accordance with an added feature of the invention, the rotary joint is a so-called wrench joint.
In accordance with another feature of the invention, the valve is a multiway valve switchable by the setting device into a first switching position and a second switching position.
In accordance with a further feature of the invention, the lid has a rotatable lid disk that is a bayonet disk forming the wrench joint and provided with so-called wrench elements.
In accordance with yet another feature of the invention, the ink-supply device includes a venting device for venting the internal space in a third rotary position of the rotary joint, that is located between a first rotary position xe2x80x9ccompletely joinedxe2x80x9d and a second rotary position xe2x80x9creleasedxe2x80x9d, while the rotary joint has not yet been released.
In accordance with yet a further feature of the invention, the ink-supply device includes a safety device for preventing the rotary joint from being rotated from the third rotary position into the second rotary position for as long as the internal space remains at excess pressure.
In accordance with yet an added feature of the invention, the ink-supply device includes an air pressure-sensitive sensor for signalling a presence of excess pressure in the internal space to an electronic control device.
In accordance with yet an additional feature of the invention, the ink-supply device includes an electric switch for signalling an actual switching position of the valve to an electronic control device.
In accordance with still another feature of the invention, the electric switch is actuatable by the setting device for actuating the valve.
In accordance with still a further feature of the invention, the ink-supply device includes a locking device for blocking rotation of the rotary joint when there is no cartridge in the cartridge holder, and for releasing rotation of the rotary joint when a cartridge is accommodated in the cartridge holder.
In accordance with a concomitant aspect of the invention, there is provided a printing machine including at least one ink-supply device having at least one of the foregoing features.
Thus, the ink-supply device of a printing-machine inking unit, having a pressure discharge device, including a cartridge holder for accepting a cartridge, and a lid for closing the cartridge holder, compressed air being applicable to an internal space of the pressure discharge device via a flow path provided with a valve, is distinguished by the valve being actuatable via a setting or adjusting device when the cartridge holder is closed by the lid.
An alternative thereto is an ink-supply device of a printing-machine inking unit, having a pressure discharge device provided with a lid for closing a cartridge directly, compressed air being applicable to an internal space defined by the cartridge and the lid, via a flow path provided with a valve, and the valve being actuatable via a setting or adjusting device when the cartridge is closed by the lid.
In the latter ink-supply device, during the closing operation, the lid is placed directly onto the cartridge instead of onto the cartridge holder and, for example, is screwed to the cartridge or preferably joined therewith via a wrench joint. For this configuration, cartridges can be used which are provided with threads or equipped with wrench elements. The joining or connecting elements are preferably formed close to the edge at ends of the cartridge remote from the pressure discharge opening, on the outside or inside of the tubular cartridge.
Embodiments described hereinbelow, respectively, permit a particularly advantageous development of the aforedescribed ink-supply device according to the invention.
In one embodiment, the cartridge holder and the cartridge, respectively, can be formed so as to be closed by the lid via a releasable rotary joint, the valve being actuatable via a setting or adjusting device when the rotary joint is rotated.
Any outflow of compressed air from the inactive pressure discharge device is absolutely reliably avoided. The setting or adjusting device can actuate the valve so that the compressed-air feed to the internal space is shut off when the cartridge holder is opened, and the compressed-air feed is released when the cartridge holder is closed. The valve is preferably switchable mechanically by the setting or adjusting device, in that the setting device displaces or rotates an adjusting element of the valve, for example, an adjusting push-button, due to which the valve is switched.
Assurance is thereby provided that the valve is automatically driven correctly as a function of the rotary position of the rotary joint. When the rotary joint is unscrewed and screwed tightly, the valve can be switched, respectively, in the opposite direction. When the rotary joint is released, the compressed-air feed can be interrupted by the valve, so that the inadvertent outflow of compressed air is absolutely reliably prevented. When the rotary joint is closed, the valve, in this case, releases the compressed-air feed, so that the readiness of the pressure discharge device to operate is ensured. An unclosed lid is additionally detectable more easily by the operator, in comparison with an unpressed switch knob, so that the operator can make the system ready to operate in good time, for example, by closing the cartridge holder and producing the rotary joint, before the operator begins the printing operation.
In a further embodiment, the rotary joint is a wrench joint. The wrench joint catches formlockingly by the twisting or rotation of the entire lid and a rotatable part of the lid, respectably, and the cartridge holder and a rotatable part of the cartridge holder, respectively, in one another. In this regard, it is noted that a formlocking connection is one which connects two elements together due to the shape of the elements themselves, as opposed to a forcelocking connection, which locks the elements together by force external to the elements. Preferably, a rotatable part of the lid is rotated while the cartridge holder is fixed. The wrench joint can be frictionally locking and formlocking, the force required for the frictional connection between the participating wrench elements becoming effective due to an elastic deformation of components, for example, a resilient sealing ring inserted between the lid and the cartridge holder and sealing off the internal space, or due to a deformation of the lid and the cartridge holder itself, respectively. The wrench joint holds the cartridge holder closed in a very reliable manner.
In a further embodiment, the valve is a multiway valve which can be switched into a first switching position and a second switching position by the setting or adjusting device.
In addition to the application of compressed air, the multiway valve likewise permits venting of the internal space, the application of compressed air and the venting being able to take place via different flow paths in the valve. Depending upon the switching position, assurance is provided that the internal space either has compressed air applied thereto or is vented, and is never simultaneously acted upon by compressed air and vented. In addition to the increased operating reliability, the outlay or expense for production is reduced, because an additional venting device separate from the valve is not required.
In a further embodiment, the lid has a rotatable lid disk that is a bayonet disk forming the wrench joint and provided with wrench elements.
In this regard, the wrench joint is formed as a flange-like wrench pair similar to the bayonet fittings which are conventional for joining photographic cameras to interchangeable lenses. In contrast with a screw joint, the bayonet joint can be released rapidly and rejoined again, by rotating the bayonet disk.
In a further embodiment, in a third rotary position of the rotary joint, located between a first rotary position xe2x80x9ccompletely joinedxe2x80x9d and a second rotary position xe2x80x9creleasedxe2x80x9d, the internal space is vented by a venting device while the rotary joint has yet not been released.
The venting device permits the internal space to be vented, the positive or excess pressure being dissipated in the second position before the cartridge holder and the cartridge, respectively, have been completely opened. In this manner, the abrupt escape of the compressed air and, consequently, any possibility of the already completely released lid being thrown off by compressed air, is avoided. The venting preferably occurs via the valve which, in this case, is part of the venting device. A safety device which, for example, depending upon the pressed air, locks the rotary joint, can in this case ensure that the rotary joint be rotatable from the third rotary position (middle position) into the released, second rotary position only after the internal space has been completely vented.
In a further embodiment, a sensor sensitive to air pressure is provided for signalling positive or excess pressure in the internal space to an electronic control device.
Through the intermediary of the sensor, a message can be sent to the electronic control device, so that the latter receives a signal that the valve has been opened and a cartridge has been inserted into the cartridge holder, and thus the system is made ready to operate. The internal space is partly formed and bounded, respectively, by the cartridge, it being possible for positive or excess pressure, which can be registered directly by the sensor, to build up in the internal space only when the cartridge has been accepted properly by the cartridge holder, and the latter has been closed by the lid.
In a further embodiment, an electric switch is provided, which signals the actual or current switching position of the valve to an electronic control device.
The electric switch can be provided in addition to the sensor sensitive to air pressure or, preferably, instead of the sensor sensitive to air pressure. The switch informs the control device whether the valve is opened or closed.
In a further embodiment of the invention, the electric switch is actuated by the setting or adjusting device actuating the valve.
By actuating the valve and the switch by way of a common setting or adjusting device, if the sensor sensitive to air pressure is not present, assurance can be provided that a feedback regarding the correct application of compressed air to the internal space is transmitted to the control device. The application of compressed air to the internal space is thereby registered indirectly via the switching position of the valve.
In a further embodiment, rotation of the rotary joint is blocked by a locking device if there is no cartridge in the cartridge holder, and is released when a cartridge is accommodated in the cartridge holder.
Consequently, the lid and the cartridge holder can be joined only when a cartridge has been inserted properly into the cartridge holder. The case wherein no cartridge has been inserted into the cartridge holder, or a cartridge has been inserted into the cartridge holder improperly, and the pressure discharge device is thus not closed, is readily apparent to the operator. In such a case, the operator can take the necessary countermeasures before spoilage or rejects are produced.
The ink-supply device according to the invention can be used in sheet-fed and web-fed rotary printing machines, which can operate, for example, in the letterpress or offset-printing process.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an ink-supply device of a printing-machine inking unit, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, wherein: